As members of the press file into the Moscone Center for the Worldwide Developers Conference keynote Monday, one reporter snapped a picture of a pair of iMacs onstage at the event, appearing to show off the desktop for Apple's next major Mac operating system update, expected to be called "Yosemite."

The iMacs with a wallpaper showing off the park's iconic "Half Dome" formation were published on Twitter Monday by Mashable's Lance Ulanoff. Presumably, the onstage Macs will be used to showcase OS X 10.10 to developers and press in attendance for the keynote.

The next major release of OS X is just one of the items expected to receive attention Monday, with Apple's iOS 8 platform also set to take the stage. Apple also has a number of cars on display at the show, suggesting that CarPlay connectivity between the iPhone and compatible vehicle infotainment systems will be showcased.

The keynote kicks off at 10 a.m. Pacific, 1 p.m. Eastern, and will be streamed live by Apple. AppleInsider is also in attendance, and will be offering live commentary of the event, as well as full coverage of the conference throughout the week.